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Assessing Winter Forages: Quality and Quantity

UK - Concentrate feed prices may be lower this winter, but the most efficient production will result from knowing the value of grass and forages on the farm and using them well in the months ahead.

This is according to EBLEX senior livestock scientist Liz Genever who states that early autumn is the time to assess forage and grazing availability and send forage samples for testing.

"Then it is possible to make a plan for grazing and forage use, which can address any predicted shortfalls in quantity or quality of feed available," advises Dr Genever.

Bales of silage or hay can be easily counted. However, it is vital to weigh some bales, as they vary between fields, cuts and balers. Silage clamp contents can also be estimated, by measuring the volume filled and using conversion tables to work out the tonnage.

A lab analysis will allow the best forage to go to the stock which need it most and ensure rations can be balanced. When taking a sample, follow the instructions in the analysis pack carefully, to ensure a representative sample is sent off. A guide to taking and interpreting analysis results is also available in the BRP manual Making Grass Silage for Better Returns.

Supply as much information as possible about the forage to be tested (e.g. grass only or red clover, first or second cut, bale or clamp and additive used) to allow the lab to select the most appropriate analysis calibration. A list of labs is available on the EBLEX website.

For grass-based wintering systems, a feed budget is crucial, as it will allow decisions to be made early. The budget is based on the number of animals, their weight and predicted intakes with information on the area being grazed, plus any conserved forages or concentrates being used.

Through the winter, pasture cover can be monitored against targets, with feeding plans altered to make sure the optimum target spring pasture cover is achieved.

To prepare a budget, walk the fields to be used for winter grazing and calculate an average pasture cover as a starting point. The new EBLEX sward stick, which converts compressed sward heights kilograms of dry matter per hectare (kg DM per ha) can help. For a free one email EBLEX BRP.

The expected farm cover at the end of each month can then be calculated from the difference between grass growth and stock daily intake in kg DM per ha, multiplied by the number of grazing days in that month and then added to the previous month’s cover.

The results can be plotted on a graph to predict what is likely to happen to the cover over the winter. An example is available in the BRP manual Planning Grazing Strategies for Better Returns or the BRP+ document on All-Grass Wintering.

When doing a winter feed budget, run through various grass growth predictions for best and worst case scenarios and to review how supplements might be used.

For example

Growing cattle at 350kg have a predicted intake of 10.5kg DM per day (350 x 3 per cent of bodyweight), so a group of 30 has a demand of 315kg DM per day. If one 250kg DM silage bale lasts them two days, then they will also need to eat 6kg DM of grass per day each ((315-125)/30).